Tomatic infeed centerless grinder



Feb. 21, 1939. A. J. GRAF ET AL 2,147,391

AUTOMATIC INFEED CENTERLESS GRINDER Filed July 16, 1937 5 Sheets-Shqet l INVENTORS A NDREW J. GRAF CLIFFORD L. SCHULTE W ATTORNEY.

Feb. 21, 1939. A, J GRAF r AL 2,147,891

'AUTOMATIC INFEED GENTERLESS GRINDER Filed July 16, 1937 5 Sheets-Sheet 3 INVENTORS- REW 1? GRAF BY IFFOAD L. Sam/L TE WWW ATTORNEY.

Feb. 21, 1939. A J GRAF H'AL 2,147,891

AUTOMATIC INFEED CENTERLESS GRINDER Filed July 16, 1937 5 Sheets-Sheet '4 INVENTORS ANDREW d. GRAF BY CLIFFORD L. SCHULTE ATTORNEY.

Feb; 21,1939. r A. J. GRAF ET AL 7 2,147,891

1 AUTOMATIC INFEED CENTERLESS' GRINDER Filed July: 16-, .1937 Y 5 Sheets-Sheet 5 I INVENTORS ANDREW J. GRAF BY v curr oku L. ScHuL TE ATTORNEY.

Patented Feb .21, 1939 V 2,147,891 rromrro men csn'rnmnss GRINDER Andrew J. Grai, Nor-wood, and Cliflord L. Schulte, Bossmoyne, Ohio, assignors to- Cincinnati Grinders Incorporated, Cincinnati, Ohio, a corporation of Ohio \pplicationJuly 16, 1937, Serial No. 154,046

This invention relates to grinding machines and more particularly to improvements in automatic centerless grinders.

One of the objects of this invention is to provide an improved and simplified mechanism for obtaining greater advance and retractive movements between the grinding wheels of a centerless grinder of the infeed type.

Another object of this invention is to provide an improved hydraulic operating and control mechanism for governing the movements of the regulating wheelin a centerless grinder of the infeed type. A further object of this invention is to provide a control mechanism for producing a complete automatic cycle in an infeetiv type centerless grinder, including loading and ejecting of the work, which may be controliedby a single cam. An additional object of this invention is to provide an improved automatic infeed type centerless grinder for automatic grinding of work pieces which do not lend themselves to through feed grinding principals.

Other objects and advantages of the present invention should be readily apparent by reference to the following specification considered in conjunction with the accompanying drawings illus-.

trative of one embodiment thereof, but it will be understood that any modifications may be made in the specific structural details within the scope of the appended claims without departing from or exceeding the spirit of the invention.

Referring to the drawings in which like reference numerals indicatelike or similar parts:

Figure 1 is an elevation of a'centerless grinder embodying the principles of this invention.

Figure 2 is a plan view of the machine shown in Figure 1.

Figure 3 is a section through the cam controlled mechanism as viewed on the line 3-3 of Figure 2.

Figure 4 is an nlarged detail section taken on the line 44 of Figure 3.

Figure 5 is an enlarged section taken on the line 5-5 of Figure 2. v

Figure 6 is an enlarged detail view of the control'cam.

Figure '7 is a section through the work loading mechanism as viewed on the line l1 of Figure 1.

Figure 8 is a section on the line '8-8 of Figure '1.

Figure 9 is a diagramma ic view of the hydraulic control circuit.

Grinring operations on a centerless grinder are usually carried out by two different methods, one of which is the through feed method and the other the infeed method. The through feed method is used for grinding cylindrical work, which passes through the grinding throat in a. continuous stream. The infeed method is utilized for grinding workpieces which either have an obstruction thereon which is larger in diameter than the portion being ground, or have a contoured surface, which necessitates their remaining in a fixed axial position relative to the wheels.

When the latter method is used, the wheels must i be retracted for the purpose; of removing and inserting work, and then' brought together to form the grinding throat, afterwhich an additional movement or inieed is effected-to accomplish the grinding operation and reduce the work to the desired size. a

This invention deals with an automatic mechanism which will effect a continuous repetition of an automatic infecd cycle including automatic positioning and ejecting of the work. In prior machines of this nature it was only necessary to provide a relatively small amount of separation between the wheels to permit withdrawal of the work, but in the present machine the work moves laterally from the work rest blade and drops between the wheels into a conveyor chute, which means that the movable wheel must be retracted a'much greater amount than heretofore in order to permit work ejection in this manner. Due to this larger movement, prior mechanisms have been found inadequate and therefore an improved structure has been provided by the present invention, whereby a large movement may be easily and quickly efiected, and one of the features of this invention is to provide a mechanism which will execute the positioning movements at a rapid rate and the grinding movements at a desirable slow rate.

Referring to Figures 1 and 2 of the drawings, the reference numeral l0 indicates the bed of a centerless grinder having a grinding wheel II, and a regulating wheel I2, supported on the top thereof for relative movement toward and from one another, and with respect to a work rest blade l3 which is located between the wheels. On the present machine the grinding wheel ll rotates in a fixed position, and the regulating wheel I2, which rotates at a much slower speed than the grinding wheel, and serves the function of rotating the work, is rotatably j'ournaled on a movable slide it for relative movement with respect to the grinding wheel to permit insertion and removal of the work.

The slide l4, as more particularly shown in Figure 5, carries a nut 15, in which is threaded a screw I6 having an axially extending shank H. The shank IT has a piston l8 secured thereto which is reciprocably supported in a cylinder IS. The cylinder is integral with a bracket 20 which is attached to the bed ID. The shank l'l extends through the rear of the bracket 20 for receiving an operating hand wheel 2 I which serves work and the amount of room necessary to clear the work rest blade, and thus acts to determine the situs of the power stroke to be effected by the piston. The piston ll serves to move the regulating wheel toward the grinding wheel, while another piston 22 is provided for effecting the return stroke. The piston 22 is connected by a piston rod 23 to the slide l4. ,The cylinder 24 which contains this piston is the same length as the total stroke of the slide l4, because a relative adjusting movement between the piston 22 and the slide l 4 cannot be efl'ected as in the case of the piston l8. p

The work piece being ground in this machine is indicated by the reference numeral 25 in Figure 7, and it will be noted that the work piece has a conoidal shaped end 26. The work is inserted between the grinding wheels with this end first, and the grinding wheel II has a parabolic shaped portion 21 which is complementary to the shape to be ground on the ends of the work piece. It is due to the converging shapes of the two grinding wheels that prevents work pieces of this nature from being ground by the through feed method.

The work pieces are stacked in a hopper 28 and a reciprocable plunger or work pusher 29 is supported adjacent to the bottom of the hopper for moving a work piece from the hopper to the grinding throat between the wheels; After the plunger has moved a work piece into the grinding throat, it remains in the dash and dot position indicated by the reference numeral 30 in Figure 7 during the grinding operation to serve as-means for holding the work in proper axial position with respect to the wheel, because due to the converging shapes of the grinding wheels, an axial thrust is developed which would tend to cause the work to move backward. The manner in which the work piece 25 is supported in the grinding throat of the machine is, more particularly shown in Figure 8. It will be noted that the work rest blade II has an angular top II, and that the clockwise rotation of the grinding wheel urges the work piece downward against this top and into engagement with the regulating wheel. This insures that the work will be held in suflicient frictional engagement with the work rest blade maybe adjusted to the proper position in front of the grinding wheel. The lower slide may then be clamped to the bed l0 and the upper slide moved to vary the position of the regulating wheel. a a

When the work has been ground to size, it will be apparent from Figure 8, that the regulating wheel l2 must be retracted a suflicient amount that the work piece 25 may fall oil! of the angular top work rest blade into the work receiving chute 23. It will be apparent that the amount of this movement must be equal to the distance between the side 34 of the work rest blade and a line 35 tangent to the periphery of the grinding wheel at the point of contact with the work. This distance is indicated by the reference numeral 36, and determines the minimum stroke of the piston i8 which translates the regulating wheel.

The work pusher 29 is actuated by a-piston 31 contained in the cylinder 38, as shown in Figure 7, and connected by a piston rod 39 to the pusher 29. This cylinder has a pair of ports 40 and 41 at opposite ends which are connected by channels 42 and 43 respectively to ports 44 and 45 of a reversing valve indicated generally by the reference numeral 46. This reversing valve has a pressure port 41 which is supplied with fluid from a pump 48 having an intake 49 through which fluid is withdrawn from areservoir 50. The valve also has a pair of return ports 5| and 52 which are connected to the'return line 53 leading to the reservoir 50. A plunger 54 is reciprocably mounted in this valve and is held by fluid pressure into engagement with an operating arm 55 which is carried by the shaft H. The plunger has a pair of annular grooves 55 and 51 formed therein which serve to alternately connect the pressure port 41 to ports 44 and 45 to eflect alternate advance and retraction of the work'pusher 29.

The advancing movement of piston I8 is controlled by a servo-valve indicated generally by the reference numeral 58 and consisting of movable sleeve 59 and an independently movable plunger 60. The sleeve has a first wide annular groove 6| which is in constant communication with a passage 62 terminating in an annular groove 63 which is in communication with the-pressure port 41; a second wide annular groove 64 which is in constant'communication with a channel 65 leading to the right hand end of cylinder I9; and a third annular groove 66 which is in constant communication with an exhaust channel 61. Radial holes are drilled in the groove forming a port 68 which is normally closed by a spool 69 formed on the plunger 80.

The spool 69 is substantially the same width as the port I so that upon movement of the plunger Olas to the left, the pressure will flow from the port 41 through the passage 63, groove 6|,

- port 1., and annular groove II to the port 68,

and thereby through the passage 65 to the cylinder II to cause actuation of piston l8. Upon movement of the spool to the right, the port 68 will be connected by the annular groove 12 in plunger", to the exhaust port 13. The plunger 60 is held into engagement with a second. plunger 14 which carries a roller 15 bearing on the periphery of 'a cam 16. The plunger 14 is slidably mounted in the open end of sleeve 59, and a key TI is provided for holding the plunger 14 against rotation in the sleeve so as to maintain the axis of the roller 15 parallel to the axis 01. the shaft 11 which supports the cam. The sleeve is fixed with the member 55. It will now .be apparent that if elevations are provided on the cam that the plunger 80 can be moved, as to the left, independently of the sleeve to cause fluid pressure to flow to cylinder I9, and that upon actuation of the piston I8, the member 55 will cause the sleeve 59 to follow up the movement of the plunger 60 and thereby close the port 68 to stop movement of the piston.

Thus the piston I8 is a servo controlled single acting piston for causing advancing movement of the regulating wheel toward the grinding wheel.

Return movement of the regulating wheel is effected by the second piston 22 slidably mounted in a cylinder 24 and connected by a piston rod 23 to the regulating wheel slide I4. This piston is smaller in diameter than the piston I8 whereby a constant pressure can act thereon in one direction, the left end of the cylinder, as shown in Figure9, having a port 8| which is connected by channel 82 to the output of pump'48. In other words, the same unit pressure of the pump is caused to act on pistons I8 and 22, but when acting on the piston I8 its-larger area will produce a total resultant pressure which is greater than the total resultant pressure acting in the opposite direction on piston 22 and the slide will move toward the grinding wheel. The cylinder 24 has a length equal to the total length of possible movement of slide I4 because no adjustable connection is provided, whereas the piston I8 has a screw and nut connection withthe slide I4 whereby the piston I8 may havethe same starting position regardless of the longitudinal position of the slide relative to the bed.

Although the shaft I1, as shown in Figure 5, carries the piston I8 and member 55 during axial movement thereof, it is not necessary or desirable that these parts rotate, when the shaft I1 is rotated manually to effect relative adjustment of the regulating wheel slide, andtherefore antifriction bearing means have been provided whereby the shaft I1 may be rotated relative to these parts. To this end the shaft I1 is provided with a shoulder 88 and a reduced portion 84 upon which are mounted a pair of antifriction thrust bearings 85, one of which abuts the shoulder 83. The piston I8 has an internal annular rib 86 which projects between these thrust bearings, and a nut 81 is threaded on the rod l1 for clamping all of these parts against the shoulder 88 so that the piston is rigidly connected for axial movement of the shaft I1 while permitting the shaft to rotate without causing rotation of the piston I8.

The shaft "is provided with a second shoulder 88 and reduced portion 89 "upon which is mounted a sleeve 90 having a shoulder at one end which is clamped against the shoulder 88 on the of sleeve 59 whereby the sleeve is held against rotation. The connecting member 55 also has a depending portion 95 which carries a set screw 95 which forms an abutment for the reversing valve plunger 54, and by adjusting the screw 96 relative to the member 55, the point of reversal of the actuating piston, 81 for the work loader may be accurately timed with respect to the journaled within the bracket.

pressure in engagement with the connecting member 55. This pressure is hydraulic and is supplied by the pump 48, but is much lower than the pressure of the actuating fluid. This lower 'six times as-much resistance as the check valve 98 whereby the unit pressure in channel I00 will be about one-sixth of the unit pressure supplied to the piston l8. The channel I00 is connected to the spaces IN and I02 whereby this unit pressure will act on all of members 54, 59 and to hold plunger 54 and sleeve 59 in engagement with the member 55, and the plunger 60 into engagement withthe periphery of the cam wheel 16. In order to take care of any leakage, the space L03 in cylinder I9, and the space I04 in cylinder 19, are connected to a return line I05 whereby any accumulation of fluid which might interfere with proper operation of the parts may be disposed of.

In order that the work loading plunger may move at a smooth, even and controlled rate, an adjustable throttle valve I06 may be interposed in the channel 43 whereby it will control the outflow from cylinder 38 during movement in one direction and the inflow during movement in the other direction andthereby control the rate of both directions of movement.

The machine has a continuously repeating automatic cycle, and the cycle of operation is controlled by the cam 16. As shown in Figure 3, an electric motor I01 is mounted on the bracket 20, and connected by a coupling I08 to shaft I09 A spur gear H0 is keyed to the end of this shaft for driving gear III keyed to the end of shaft H2. The latter shaft carries a worm II3 intermeshing with a worm gear II4 keyed to the cam driving shaft 11. It will now be apparent that upon actuation of the motor I01, that the cam shaft will be continuously rotated at a uniform rate.

The cycle of operation of the machine will be explained, reference being had to the enlarged view of the control cam 18, as shown in Figure 6.

and the arrow I I6 indicates the direction of rota tion of the cam. The valve plungers 54 and 60 are shown in the starting position in Figure 9, and it will be noted that the port M of cylinder 38 is connected to pressure to cause retraction of the work pusher. Assuming the retractive movement to begin at the line II5 on the cam, it will be apparent that an appreciable length of-time at least will be necessary to complete this movement, and thereforethe cam is provided with a dwell II1 to insure completion of this movement. W'hen completed, the parts will be in the position shown in Figure '7, and a new work piece .25 will drop from the hopper 28 into a position in front of the pusher 29.

, The radial line II5 indicates the starting point,

It is to be understood that the plunger 80 and sleeve 59 constitute what is commonly termed a servo-motor mechanism in that displacement of the plunger 80 to the left, as viewed in Figure 9, by action of cam 18, introduces pressure by way of groove GI, port 10, groove H and port I55 to the right hand side of piston I8, moving member I1 and associate parts to the left. As sleeve 59 is coupled through member 55 with I1, it is correspondingly shifted to the left, restoring the rate of actuation of the piston.

The sharper the rise on cam 16 which is rotated at a. uniform rate, the faster the rate of movement of the plunger 60 and consequently the faster the follow-up of member I! and sleeve 59. Conversely, on reverse movement of the plunger, land 69 couples port 68 via'cannelure I2 with exhaust conduit. 61, variably throttling the relief of pressure on the right hand side of piston I8, permitting retraction of parts by the pressure in cylinder 24, the reverse follow-up of sleeve 59 correspondingly controlling the rate and extent of this retracting movement.

The cam is next provided with a rapidly rising portion III which will cause movement of the servo-valve .plunger 60 to the left as viewed in Figure 9, thereby admitting fluid to cylinder it which will cause movement of piston l8 and thereby move the regulating wheel toward the grinding wheel a sufficient amount to contract the grinding throat, Figure 8, in readiness for insertion of the next work piece. During the advancing movement of piston IS, the connecting member 55 has been following up the movement of the servo-valve plunger 60 and has been moving the reversing valve plunger 54 toward the left so that by the time the point H9 is reached on the cam 16, thereversing valve plunger 54 has been moved a suflicient distance to connect pressure port 41 to port 44. The piston 31 now advances to insert a new work piece into the grinding throat and in order to permit this movement to be completed, a dwell I20 is provided on the cam. The work is now ready to be ground and a short sharp rise III is provided on the cam for moving the work into contact with the grinding wheel.

A slow rising portion I22 is next provided on the cam whereby the regulating wheel slowly advances the work into the grinding wheel to reduce the work to size. In order to permit the grinding wheel time to clean up the work and spark out after the advancing movement of the regulating wheel has been completed, the dwell I23 is provided. With the work now ground to size, a sudden fall I is provided on the cam which permits the servo-valve plunger 60 to move toward the right, and connect port It to exhaust port 13 whereby the constant pressure in cylinder 24 may now retract the regulating wheel through action on the piston 22. By the time the retracting movement has completed, and the work has dropped off of the work rest blade into the chute 33, the reversing valve plunger SI has moved to such a position that the pressure port 41 is connected to port 45 to cause retraction of the work pusher and the next cycle of operation is ready to begin. It will now be apparent that the cam controls the rapid advance and feeding movement of the regulating wheel as well as the return movement thereof, and also causes insertion of a new work piece by power at the proper moment in the cycle.

There has thus been provided an improved power operable automatic mechanism for effecting an infeed cycle on a centerless grinding machine, including mechanism for automatically loading and ejecting the work.

What is claimed is:

1. In a grinding machine having a bed, a slide reciprocably mounted on said bed, and an abrasive wheel rotatably supported on said slide for movement to and from a work piece, the combination of means for actuating said slide, ineluding a piston and cylinder, one of which is fixed and the other connected to said slide, a second cylinder and piston having one of said parts connected to the bed and the other to said slide, a source of fluid pressure permanently connected to one of said pistons, a servo control valve for governing the flow of fluid from said source of pressure to the other piston, including a relatively movable sleeve and plunger, a cam for actuating said plunger, fluid operable means for maintaining said plunger in contact with the periphery of said cam, and a feed back connection from one of said pistons to said sleeve.

2. In a grinding machine having a bed, a slide reciprocably mounted thereon, and an abrasive wheel rotatably mounted on said slide, the combination of means for shifting said slide, including a pair of differential pistons permanently connected to said slide,a source of fluid pressure, means permanently connecting said source of fluid pressure to the smaller of said pistons, and a servo control valve mechanism for controlling the flow of fluid to and from the other of said pistons to cause advance and retraction of said slide.

3. In a grinding machine having an abrasive wheel, the combination of fluid operable means for advancing and retracting the wheel with respect to a work piece, a fluid operable work 35 loader for successively positioning work pieces in front of said wheel, a reversing valve plunger for said work loader, means continuously urging said plunger in one direction to cause retraction of said work loader, and means oprable during advancing movement of said wheel to positively shift said reversing valve in an opposite direction and cause said work loader to position a work piece in front of said wheel.

4. In an automatic infeed centerless grinder, the combination with a bed supporting a grinding wheel, a work rest blade and a regulating wheel, of a cam rotatably mounted on said bed, a prime mover, a motion transmitting train coupling the prime mover for rotation of said cam, a cam follower, fluid operable means for maintaining said follower in contact with the periphery of said cam, an infeed mechanism for said fegulating wheel coupled for control by said folower, a work loader coupled for'control by said follower, a first portion on said cam for causing rapid advance of said regulating wheel to form a grinding throat and initiate a work loading operation, a dwell on said cam for permitting the work loading operation to be completed, a second portion on said cam for rapid advancing and slowly feeding said regulating wheel toward the grinding wheel to effect a grinding operation, a second dwell on said cam to permit said grinding wheel to spark out, and a third portion on said cam for causing retraction of the regulating wheel and ejection of the finished work piece.

5. A precision grinding machine including a grinding member, a work positioning member, means for positioning work for joint engagement by said members, one of said members being movable relative to the other to effect the grinding action, and means for controlling said movement, including a pair of oppositely acting hydraulic motors, a hydraulic pressure source, means cou- 7 pling said source with one of said motors for constant unidirectional actuation thereof, and

-means for coupling hydraulic actuating medium grinding member, a work positioning member,

means for positioning workfor joint engagement by said members, one of said members being movable relative to the other to effect the grinding action, and means for controlling said movement, including a pair of oppositely acting hydraulic motors, a hydraulic pressure source, means coupling said source with one of said motors for constant unidirectional actuation thereof, and means for couplinghydraulic aetuating medium to the other of said motors, said coupling means including mechanism for variably determining the rate of change and effective pressure differential in the respective hydraulic motors and thus the rate and relative direction of movement of the grinding and work engaging members; said means including va reciprocable throttling plunger, means for controlling the re 1 ciprocation of said plunger, a sleeve valve encircling the plunger, and connections between the movable member and the sleeve whereby movement of the member shifts the sleeve to counteract the initial displacement of the plunger with respect thereto.v I

7. A precision grinding machine including a grinding member, a work positioning member, means for positioning work for joint engagement by said members, one of said members being movable relative to the other to effect the grinding action, and means for controlling said movement, including a pair of oppositely acting hydraulic motors, a hydraulic pressure source, means coupling said source with one of said motors for constant unidirectional actuation thereof, means for coupling hydraulic actuating medium to the other of said, motors, said coupling means including mechanism for variably determining the rate of change and effective pressure differential in the respective hydraulic motors and thus'the rate and relative direction of movement of the grinding and work engaging members, said means including a reciprocable throttling plunger, means for controlling the reciprocation of said plunger, a sleeve valve encircling the plunger, and connections between the movable member and the sleeve whereby -movenient of the member shifts the sleeve to counteract the initial displacement of the plunger with respect thereto, and means reacting on the plunger to prevent frictional shifting thereof by movement of the sleeve.

8. A precision grinding machine including a grinding member, a work positioning member, means for positioning work for joint engagement by said members,- one of said members being movable relative to the other to eflfect the grinding action, and means for controlling said movement, including a pair of oppositely acting hydraulic motors, a hydraulic pressure source, means coupling said source with one of said motors for constant unidirectional actuation thereof, means for coupling hydraulic actuating medium to the other of said motors, said coupling means including mechanism for variably determining the rate or change and effective pressure differential in the respective hydraulic motors and thus the rate and relative direction of movement oi. the grinding and work engaging members, said means including a reciprocable throttling plunger, means for controlling the reciprocation of said plunger, a sleeve valve encircling the plunger, and connections between the movable member and the sleeve whereby movement of the member shifts the sleeve to counteract the initial displacement of the plunger with respect thereto, and means reacting on the plunger to prevent frictional shifting thereof by movement of the sleeve, said work positioning means including a hydraulic motor, and means for coupling said motor with the source of hydraulic pressure, said coupling means including a reciprocable control valve actuable by the shiftable member in accordance with movements of the members and sleeve, and means for varying the phase relationship between the sleeve and valve movements as effected by the shifting of the member.

9. A control mechanism for determining the timed sequential operation of the shiftable parts of an automatic centerless grinder including relatively movable grinding and regulating wheels and a work shifting mechanism for intermittently positioning a work piece between the wheels, including a uni-directionally activated hydraulic motor coupled withone of the wheels of the machine for effecting their relative movement, means continuously actuating said wheel in opposition to said motor, a source-of hydraulic pressure, and means for controlling the introduction and exhaust of hydraulic pressure from the motor including a shiftable sleeve coupled with and movable-by the motor, said sleeve having spaced pressure and exhaust grooves, ports coupling these grooves with the interior of the sleeve, a plunger valve contained within the sleeve and variably determining the effective coupling of the ports with the motor, and a continuously driven variably contoured cam reacting on the plunger whereby power positioning of the motor and sleeve and thus of the associated wheel of the machine will be variably effected by hydraulic power in accordance with the cam contour determined positioning of the v machine for eil'ecting their relative movement,

means continuously actuating said wheel in opposition to said motor, a source of hydraulic pressure, and means for controlling the'introduction and exhaust oi. hydraulic pressure from the motor including a shiftable sleeve coupled with and movable by the motor, said sleeve hav ing spaced pressure and exhaust grooves, ports coupling these groo with the interior of the sleeve, a plunger valve contained within the sleeve and variably determining the effective coupling of the ports with the motor, a continuously driven variably contoured cam reacting on the plunger whereby power positioning of the motor and sleeve and thus of the associated wheel of the machine will be variably effected by hydraulic power in accordance with the cam conftour determined positioning of the plunger,

a supplemental hydraulic motor for controlling actuation of the work shitting mechanism, and means operable by the first plunger controlled motor for determining the cyclic timing and direction of actuation of said second motor.

11. A control mechanism for determining the timed sequential operation of the shiitable parts of an automatic centerless grinder including relatively movable grinding and regulating wheels and a work shifting mechanism for intermittently positioning a work piece between the wheels, including a uni-directionally activated hydraulic motor coupled with one 01' the wheels of the machine for effecting their relative movement, means continuously actuating said wheel in opposition to said motor, a source of hydraulic pressure, and means for controlling the introduction and exhaust of hydraulic pressure from the motor including a shiitable sleeve coupled with and movable by the motor, said sleeve having spaced pressure and exhaust grooves, ports coupling these grooves with the interior oi. the sleeve, a plunger valve contained within the sleeve and variably determining the eflective coupling of the ports with the motor, a continuously driven variably contoured cam reacting on the plunger whereby power positioning of the motor and sleeve and thus of the associated wheel of the machine will be variably effected by hydraulic power in accordance with the cam contour determined positioning 0! the plunger, a supplemental hydraulic motor i'or controlling actuation of the work shifting mechanism, means operable by the first plunger controlled motor for deter mining the cyclic timing and direction of actuation of said second motor, and independent means for determining the rate of actuation of said second motor.

12. In a machine oi! the character described, the combination with a translatable wheel bearing support, of means for controlling translatory movements of the support, including a limited stroke hydraulic motor having an element movable with the wheel support and a fixed element, a valve sleeve iixed for movement with the element, a plunger valve supported within the sleeve and freely movable with respect thereto, means for supplying hydraulic actuating medium to the motor by way of said plunger and sleeve valves, said plunger having a projecting actuating portion, and a cam member having a contoured surface engaging the plunger and movable in a definite path with respect thereto, said contours corresponding to the degrees of movement to be imparted by the motor to the translatable wheel support, said plunger and sleeve valves having interengaging portions shutting oil flow with respect to the hydraulic motor when motor movement of the sleeve shifts the latter into phase relation with the cam determined position of the plunger.

13. A centerless grinder for the purpose described embodying opposed grinding and regu-' movement of the terminal work engaging memher and a second hydraulic motor mechanism for effecting back and forth movement of one of said wheels, said second motor mechanism incliiding a hydraulic piston, a first valve mechanism having an extended idle stroke and terminal eilective positions for controlling reversal of the terminal work engaging member, an activating member operable by the second motor and provided with means for operating said first valve, and a servo-motor mechanism for positional control of said second motor including a sleeve valve member carried and shii'table by the activating member, a contained plunger valve within the sleeve and shiitable in exact accordance with the actuating movement to be imparted to said second motor, a rotor cam engageable with said plunger member, means for eflecting continuous rotation of the cam, and hydraulic means for maintaining the plunger in engagement with the cam, said cam having an eccentrically contoured plunger engaging surface having successive concentric and eccentric portions of increasing radii throughout the major portion of its circumference whereby successive dwells and progressively advancing movements are imparted to the plunger and hydraulically transmitted through the motor to the shiitable wheel unit substantially as and for the purpose described.

ANDREW J. GRAF. CLIFFORD L. SCHULTE. 

